郭艳萍，赵金安

采用分光光度法通过测定黑鸡心葡萄酵素天然发酵过程中不同阶段的总酚含量、还原能力及其对DPPH·、·OH、O2-·、ABTS自由基的清除率来评价天然酵素的抗氧化性能。结果显示：黑鸡心葡萄天然酵素在发酵过程中总酚含量上升,对DPPH自由基、O2-·、·OH和ABTS自由基清除能力均呈逐渐增加趋势,发酵前后分别提高了6.84%,19.82%、7.32%和14.81%增幅较大,同时显示出与酵素总酚含量的变化有明显的正相关性。     

不同粒色青稞酚类化合物含量与抗氧化活性的差异及评价

为了比较不同粒色青稞中游离态及结合态酚类化合物的含量及其抗氧化活性的差异。选用52份不同粒色青稞种质资源,采用化学法分析其青稞全籽粒中游离态及结合态总酚、总黄酮含量,通过DPPH、ABTS+·自由基清除能力及FRAP铁离子还原能力评价其体外抗氧化能力差异,利用主成分分析法客观评价其酚类化合物含量及抗氧化活性的品种排名。结果表明:结合酚是有色青稞酚酸的主要存在形式,游离黄酮是青稞中黄酮类物质的主要存在形式,组间含量差异显著,黑色组青稞的总酚类化合物含量较高;不同形态酚类物质对自由基清除能力的强弱具有选择性,游离态酚类化合物含量在一定程度上决定DPPH和ABTS自由基清除能力大小,FRAP铁离子还原能力受青稞中游离态及结合态酚类化合物含量的共同影响;不同粒色组青稞的酚类化合物含量及抗氧化活性存在品种间差异,主成分分析筛选出紫色、蓝色、黑色、黄色组青稞中酚类物质含量及抗氧化活性最高的品种分别为云青2号、循化亮蓝、947和短白青稞。     

微波辅助提取猕猴桃果渣总黄酮及其抗氧化活性

以猕猴桃酿酒发酵后的果渣为原料,采用响应面法优化猕猴桃果渣总黄酮的微波辅助提取工艺,并测定其对DPPH·和ABTS+·的清除率,评价最佳工艺条件提取的总黄酮的抗氧化活性。结果表明,猕猴桃果渣总黄酮提取的最佳工艺条件为乙醇浓度50%、提取温度66℃、提取时间16 min,在此条件下,总黄酮得率为3.02%。猕猴桃果渣总黄酮提取物对DPPH·、ABTS+·具有不同程度的清除作用,当总黄酮提取物浓度为30.16 μg/mL时,对DPPH·清除率为83.08%,当总黄酮提取物浓度为12.08 μg/mL时,对ABTS+·清除率为97.36%,表明猕猴桃果渣总黄酮具有较好的抗氧化活性。     

黄茶多糖的分离纯化及其抗氧化活性研究

该文对黄茶进行分离纯化,并对其抗氧化活性进行研究。对黄茶进行热水浸提、70%乙醇醇沉得到黄茶70部位的粗多糖（YT70）,利用阴离子交换柱对YT70进行分离纯化得到YT70-1,进一步对YT70-1进行DPPH·、ABTS+·、·OH的清除试验以及总还原力能力测定试验。结果表明YT70的糖含量为43.3%,YT70-1的单糖组成为甘露糖、鼠李糖、葡萄糖醛酸、葡萄糖、半乳糖、木糖、阿拉伯糖及岩藻糖。YT70-1对DPPH·、ABTS+·和·OH的清除率与质量浓度呈量效关系,且总还原能力与浓度成正比。在浓度为20 mg/mL时,YT70-1对DPPH·、ABTS+·和·OH的清除率分别为48.7%、77.01%和39.67%,还原力为0.415。YT70-1对ABTS+·的IC50值为3.87 mg/mL。因此YT70-1具有一定的体外抗氧化活性,能够清除DPPH·、ABTS+·和·OH,并且清除能力随多糖浓度的增大而增加。     

桑叶黄酮的双水相萃取及其抗氧化活性研究

为提高乙醇-水提取物中桑叶黄酮纯度,该研究利用乙醇-无机盐双水相萃取技术对桑叶黄酮粗提物（mulberry flavone extract,MFE）进行分离纯化。通过单因素试验和Box-Behnken响应面试验对萃取工艺条件进行优化,以·OH、ABTS+·、DPPH·和 O2-·清除率为指标,比较萃取前后的桑叶黄酮（mulberry leaves flavone 1、2,MLF1、MLF2）的抗氧化活性变化。结果表明,双水相萃取体系最佳工艺条件为乙醇质量分数36%、硫酸铵质量分数17%、MFE添加量 5 mg/mL;上述条件下相比 R=1.84±0.17,分配系数 K=11.82±0.34,萃取率 Y=（95.74±0.58）%。体外抗氧化活性试验结果显示：除O2-·清除能力略低于芦丁外,MLF2对·OH、ABTS+·、DPPH·清除率均高于芦丁,且MLF2的抗氧化活性指标均高于MLF1。综上所述,双水相萃取法可用于萃取桑叶黄酮,其抗氧化活性可有效增强。     

微波辅助低共熔溶剂提取鹰嘴豆中黄酮及其抗氧化活性的研究

以鹰嘴豆为原料,氯化胆碱基低共熔溶剂为提取剂,采用微波辅助技术提取鹰嘴豆中的黄酮类物质,探究氢键供体种类、氢键供体和受体的摩尔比、料液比、低共熔溶剂体系含水量、微波功率及微波时间对鹰嘴豆黄酮得率的影响,通过单因素实验和响应面优化试验确定了鹰嘴豆中黄酮类物质提取的最佳工艺。结果表明,以氯化胆碱为氢键受体,柠檬酸为氢键供体构建低共熔溶剂体系,二者摩尔比为 1:2,低共熔溶剂体系含水量30%(V/V),料液比1:22 g/mL,微波功率为675 W,微波时间235 s,此时鹰嘴豆黄酮得率为2.49 mg/g,提取率可达90.55%,优于传统醇提法。体外抗氧化实验发现不同浓度的鹰嘴豆黄酮类化合物均具有一定的还原能力,以V_C为阳性对照组,鹰嘴豆黄酮类化合物能显著清除DPPH·、·OH、ABTS+·,随着浓度的增加,鹰嘴豆黄酮对DPPH·的清除率呈上升趋势,当黄酮浓度为0.05 mg/mL时,对·OH 的清除率达到最大,为94.39%,当黄酮的浓度为0.15 mg/mL时,鹰嘴豆黄酮的ABTS+·清除率最大,为73.83%。综合说明鹰嘴豆中黄酮类化合物具有良好的抗氧化活性。     

高钙菜黄酮的分级分离各级分的抗氧化活性

以抗坏血酸和叔丁基羟基茴香醚做阳性对照,采用二苯代苦味肼基自由基(DPPH·)、羟自由基(·OH)、超氧阴离子自由基(O₂-·)、还原力、2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐阳离子自由基(ABTS+·)和总抗体外抗氧化模型,主成分分析综合评价高钙菜总黄酮各级分(乙酸乙酯相、正丁醇相、氯仿相和水相)的抗氧化活性。结果显示,在各体外抗氧化活性指标的测定中,各萃取相的抗氧化活性均随着黄酮浓度增加呈现上升趋势,其中ABTS+·的清除能力最强,高达99.72%±0.10%,与抗坏血酸清除能力相近。乙酸乙酯相的·OH清除率、O₂-·清除率、总抗氧化FRAP值、还原力及ABTS+·清除率要显著优于其它各萃取相,氯仿相的DPPH·清除率显著优于其它萃取相。主成分分析综合评价显示,乙酸乙酯相抗氧化活性最佳。显色反应结合红外光谱分析,初步判定乙酸乙酯相和正丁醇相可能为黄酮醇类。高钙菜总黄酮具有较强的抗氧化活性,可作为良好的健康食品原料开发及利用。     

桑葚发酵前后酚类组成变化及其抗氧化活性分析

目的：旨在分析桑葚饮料发酵前后酚类物质的组成变化和抗氧化功能差异。方法：利用毕赤酵母菌(Pichia kudriavzevii)和融合魏斯氏乳酸菌(Weissella confusa)通过二次发酵桑葚制备桑葚饮料，比较桑葚发酵前后酚类物质对DPPH、OH、ABTS+自由基的清除能力及还原力，并通过非靶向代谢组学技术对不同组别样品差异代谢物进行鉴定，进而探究发酵前后酚类物质组成变化与抗氧化性能之间的相关性。结果：发酵后桑葚酚类物质(1 mg/mL)对DPPH自由基清除率由发酵前的45.97%±2.23%提高到59.01%±3.59%(P<0.05)；对OH自由基清除率由发酵前的68.68%±1.23%提高到78.55%±0.57%(P<0.05)；发酵后的桑葚饮料中酚类物质的还原力显著提高(P<0.05)；发酵前后的酚类化合物对ABTS+自由基清除能力无显著差异(P>0.05)。从发酵前后桑葚酚类物质中共筛选出46种差异代谢物，包括3种花色苷类、10种酚酸类、18种类黄酮及15种其它酚类物质，其中发酵后上调和下调的代谢物分别为26种和20种，共涉及4个相关代谢通路...     

不同品种龙眼果肉酚类物质的抗氧化活性比较

为研究不同龙眼品种资源中酚类物质、黄酮类化合物含量及其抗氧化性差异,选取广东省农业科学院果树研究所龙眼资源圃的24个龙眼品种,分析其果肉中游离态和结合态总酚、总黄酮物质的含量,采用DPPH自由基清除能力、ABTS总抗氧化能力、FRAP抗氧化能力和氧自由基吸收能力ORAC四种不同方法评价其体外抗氧化能力差异;不同龙眼品种果肉总酚、总黄酮含量与DPPH、ABTS、FRAP、ORAC四种不同方法测定的抗氧化能力的变幅和变异系数较大,呈现出显著的基因型差异;不同品种龙眼果肉的多酚和黄酮的含量分别与ABTS自由基清除能力、FRAP和ORAC呈极显著(p0.01)正相关关系,而与DPPH自由基清除能力的EC50值呈极显著负相关关系(p0.01)。采用快速聚类法将24个不同品种的龙眼聚成多酚及总黄酮含量和抗氧化能力差异显著的三大群类。不同品种龙眼果肉游离态和结合态酚类物质含量与其抗氧化活性均呈显著正相关关系,提示酚类物质是龙眼果肉抗氧化活性的主要成分;酚类物质和黄酮类物质在龙眼果肉中主要以游离态存在,其中结合态平均占总酚含量的17.45%。     

动态高压微射流辅助提取对鱼鳞多糖抗氧化活性的影响

采用动态高压微射流技术辅助提取鲤鱼鱼鳞多糖,以DPPH·、·O₂-、ABTS+·、·OH清除能力和Fe3+还原能力为评价指标,研究其对鲤鱼鱼鳞多糖抗氧化活性的影响。结果表明:动态高压微射流处理可以有效降低物料的平均粒度,粒径由未经处理的499.80 nm降低到192.57 nm;进而提高鲤鱼鱼鳞多糖的得率,当处理压力为130 MPa时,多糖得率达到7.81%。随着处理压力的提高,多糖提取液对DPPH·、·O₂-、ABTS+·和·OH的清除率以及Fe3+的还原能力逐渐增强,当处理压力为110 MPa时,DPPH·、·O₂-、·OH的清除率和Fe3+的还原能力最高分别达到了86.04%、61.23%、90.59%和0.64(OD值),当处理压力为150 MPa时,对ABTS+·的清除率达到89.58%,均显著高于空白对照组(P<0.05)。动态高压微射流辅助提取可以有效提高鲤鱼鱼鳞多糖的得率和体外抗氧化能力,本研究可为动态高压微射流技术在天然活性多糖辅助提取方面的应用提供理论依据和技术支撑。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.